Treating abdominal and pelvic cancer surgery patients with Lovenox(r) (enoxaparin sodium; also known as Clexane(r)) to prevent venous thromboembolism (VTE) for four weeks, compared to one week, reduces the incidence of thromboembolic complications by 60% without compromising safety, according to a study released today at the International Society on Thrombosis and Haemostasis (ISTH) meeting.

"Patients who undergo abdominal surgery for cancer are particularly vulnerable to thromboembolic complications," said David Bergqvist, MD, Academic Hospital, Uppsala, Sweden, and lead author of the study presented at ISTH. "This is valuable information for patients and clinicians alike. Since the surgical procedure itself is inherently risky, they need to ensure that every possible precaution is taken to minimize all other risk."

In 2000, approximately 763,000 people were diagnosed with stomach cancer worldwide. Surgery is the most common treatment. This surgery is often a high-risk procedure of prolonged duration, with VTE an important cause of death in cancer patients.

Although treating hospitalized patients with Lovenox immediately after surgery has become a routine practice, the risk of thromboembolic complications remains high for several weeks after surgery. In a 1988 study, it was found that 25% of patients undergoing major surgery developed DVT in the six weeks after discharge, although 95% had received prophylaxis while they were hospitalized.

This prospective, placebo-controlled, double-blind randomized trial study presented today evaluated the safety and efficacy of an eight day vs. a 28-day regimen of thromboprophylaxis using Lovenox(r). 505 patients undergoing surgery for abdominal cancer received Lovenox (40 mg sc) daily until day eight, when they were randomly assigned to either continued enoxaparin prophylaxis or placebo for another 21 days.

Bilateral venography (radiographic demonstration of a vein) was systematically performed on day 28 unless symptoms of venous thromboembolism occurred earlier, in which case venography or other objective documentation of thromboembolism was required.

The primary efficacy endpoint was the incidence of post-operative deep-vein thrombosis or pulmonary embolism on day 28. The primary safety endpoint was the incidence of hemorrhage during the double-blind period.

Of the 332 patients evaluated for efficacy, 165 received enoxaparin for another 21 days. There was a significant 60% reduction in venous thromboembolism (VTE) with one month vs. one week of enoxaparin, both at day 28 (12.0 vs. 4.8%, P=0.02) and at 3 months (13.8 vs. 5.5%, P=0.010). Three months after randomization, three patients in the enoxaparin group and six patients in the placebo group had died. There were no significant differences in the incidence of hemorrhage or other complications during either the double-blind or follow-up period.

Deep-vein thrombosis is a significant complication of major surgery. It is often a "silent" disease, with approximately 25% of DVT patients remaining asymptomatic. In the short term, DVT can lead to suffering and death from pulmonary embolism. In the long-term DVT can be further complicated by recurrent VTE - a condition in which a blood clot forms in a vein and becomes detached and lodges at another point - or post-thrombotic syndrome (PTS). The clinical manifestations of PTS range from edema (excessive water retention) and pain to leg deformity and leg ulcers. Up to 80% of patients experience PTS following DVT and 3%-10% experience severe PTS or leg ulceration.